Frequently transportation hubs such as subway platforms or train stations, etc, or commercial businesses such as banks, etc. present a video display to travelers or customers while the traveler or customer awaits service. Presently, these video display systems employ conventional video recording technology, such as video tape or video disk players, for storing and generating the video images presented on the video monitors.
To keep the programs displayed on such video monitors current and to vary the programs so travelers or customers don't become bored, programs are changed frequently, even daily. Because these video display systems employ conventional video technology for storing and generating the video images, changing the program displayed on the video monitors requires that an individual periodically visit each site and manually change a video tape or disk.
U.S. Pat. No. 5,027,400, that issued Jun. 25, 1991, on an application filed in the names of Toru Baji et al. ("the Baji et al. patent"), discloses a multimedia bidirectional broadcasting system that distributes motion picture data using a broadband ISDN communication channel. The system depicted in FIG. 3 of the Baji et al. patent, maintains a motion picture program data base at a "broadcasting station" for transmission over broadband ISDN communication channels in response to requests received at the broadcasting station from subscriber systems. The subscriber system disclosed in the Baji et al. patent includes a decoder for decoding the compressed video data and a television monitor for displaying the resulting images.
In addition to the broadcasting station disclosed in the Baji et al. patent, a PCT patent application entitled "Adaptive Video File Server and Methods for Its Use," filed Feb. 11, 1992, in the names of Mark C. Koz and Masato Hata, PCT Patent Application No. PCT/US92/01084, discloses a video file server or broadcasting station that includes both a random access data storage subsystem and an archive data storage subsystem for storing compressed video data. In response to commands from subscriber systems, the video file server of this PCT patent application transmits compressed video data to the subscriber systems over ISDN communication channels, or receives compressed video data therefrom in accordance with a variety of different image data compression standards. This first PCT patent application disclosing the video file server is incorporated herein by reference.
Another PCT patent application entitled "Adaptive Video Subscriber System and Methods for Its Use," filed Feb. 24, 1992, in the names of Mark C. Koz and Masato Hata, PCT Patent Application No. PCT/US92/01446, discloses a subscriber system that includes a communication subsystem for receiving and transmitting compressed data via an ISDN communication channel. This subscriber system generates a video signal from the compressed video data received from the ISDN communication channel to produce a visible image on a display such as a cathode ray tube ("CRT") included in a television or red-blue-green ("RGB") monitor, a liquid crystal display panel, a plasma panel, or any other suitable display device. The subscriber system disclosed in this PCT patent application also includes a SCSI controller that provides the subsystem with a SCSI port. This SCSI port permits attaching a variety of different computer peripheral devices including hard disks or an optical disk unit to the subscriber system for storing compressed video information received from the ISDN communication channel. This second PCT patent application disclosing the subscriber system is incorporated herein by reference.
Using the subscriber system disclosed in PCT Patent Application No. PCT/US92/01446 for generating video images displayed at transportation and commercial facilities instead of conventional video recording technology permits electronically distributing, over an ISDN communication channel rather than manually, the program displayed at such remote locations. Moreover, electronic program distribution to these subscriber systems can take place at convenient times of day such as when there are few or no travelers or customers present, and/or when telephone system usage is low. However, even though such a system distributes compressed video data, transmitting a new program from a central location to a subscriber system over an ISDN basic access communication channel requires a significant amount of time. For example, transmitting 10 minutes of compressed, high quality video images over a pair of ISDN basic rate communication channels takes approximately one and one-half hours.
Because a major metropolitan area may include a large number of video display installations whose programs must be changed frequently, even daily, the long transmission time to distribute compressed video data directly to subscriber systems requires a large number of broadcasting stations or video file servers. Because of their present cost, it is economically impractical to dedicate a large number of broadcasting stations or video file servers to distributing video programs over ISDN basic access communication channels when the broadcasting station or video file server may be in use for only a small portion of each day.
While using a communication channel having a higher data transmission rate than an ISDN basic access communication channel, e.g., an ISDN primary access communication channel, significantly reduces the data transmission time and therefore, correspondingly, reduces the number of broadcasting stations or video file servers required to distribute programs, the expense of such a communication channel is also be prohibitive since it will be in use for only a short interval each day.